1. Field of the Invention
The present invention relates to an ultrasonic diagnostic apparatus for scanning a three dimensional region of a detected object and producing three dimensional image data of a figure and function of a specific internal organ, such as the heart, based on received signals obtained from the scanning.
2. Discussion of the Background Art
Recently, an ultrasonic diagnostic apparatus can display an image to provide functional information about an internal organ, specifically the heart. For example, one idea involves a method to determine a condition of ischemic heart disease by detecting volume information of an interior wall movement of the heart muscle. This has been known as the tissue Doppler image method, in which speed of a heart muscle is displayed with brightness and color changing in accordance with elapsed figure deforming. In the tissue Doppler imaging (TDI) method, a portion displayed without brightness and color can be judged as a portion which is not actuating so much such and may evidence an infarction of the heart muscle.
On the other hand, there is an idea for displaying an ultrasonic contrast medium image injected into a detected object by a harmonic imaging (HI) method and other methods. In harmonic imaging, it is possible to detect a portion into which the ultrasonic contrast medium does not flow so much with blood, thereby to obtain a visualization of perfusion.
Further, there recently has been developed an ultrasonic diagnostic apparatus for collecting and displaying three dimensional figure information in an organism, such as a B-mode image, in real time. In order to proceed in real time, there is employed a multi-direction simultaneous receiving technique for transmitting a broadly spreading wide ultrasonic beam and simultaneously forming a plurality of beams of a directivity different from each other as receiving beams.
However, there still exists a problem to be solved in order to form a three dimensional functional image for showing functions of the heart by the TDI method, the HI method and so on, Unless an unusual portion in the heart, where an infarction of the heart exists and reflux of blood occurs, can be detected, the imaging result can not be utilized for diagnosis. In order to solve the problem, a two dimensional functional image has been overlapped on a two dimensional figure image in the field of two dimensional techniques.
In a field of the three dimensional technique, if a three dimensional functional image is overlapped on a three dimensional figure image in a way similar to the two dimensional technique, one image interrupts viewing of the other image, and vice versa. That is, a part of the functional image overlapped with the figure image and a part of the figure image overlapped with the functional image mutually interrupt viewing one image. As the result, a location of an unusual portion can not be specified and the likelihood of missed detection of the unusual portion is increased.